Today, many notebook computers have metal outer housings. Due to the electrical conductivity of such housings, it is possible for leakage current generated by the computer's power system to reach the outer housing and discharge into the computer user, particularly when the computer is being powered with an ungrounded power cable connected to a wall outlet. In such a case, the user acts as a ground path for the computer into which the leakage current is discharged. Although such discharge is neither hazardous nor painful to the user, it is noticeable and can be unsettling.